It shouldn't be much slower at all, although depending how quickly you load Construct after a new update is out there's a small chance the files aren't cached yet by our CDN and are being served directly by our website.
It's impossible to tell without seeing the requests which is hard to do, so for now I would assume it's just a random blip. If you can actually do measurements over a few releases and send me the results I can look into it further.